Common Heavy Metals: Sources and Specific Effects Cadmium

Cadmium is an element that occurs naturally in the earth's crust. Pure cadmium is a soft, silver-white metal; however cadmium is not usually found in the environment as a metal. It is usually found as a mineral combined with other elements such as oxygen (cadmium oxide), chlorine (cadmium chloride), or sulfur (cadmium sulfate, cadmium sulfide). These compounds are solids that may dissolve in water but do not evaporate or disappear from the environment. All soils and rocks, including coal and mineral fertilizers, have some cadmium in them. Cadmium is often found as part of small particles present in air. You cannot tell by smell or taste that cadmium is present in air or water, because it does not have any definite odor or taste.

Cadmium can enter the environment in several ways. It can enter the air from the burning of coal and household waste, and metal mining and refining processes. It can enter water from disposal of waste water from households or industries. Fertilizers often have some cadmium in them and fertilizer use causes cadmium to enter the soil. Spills and leaks from hazardous waste sites can also cause cadmium to enter soil or water. Cadmium attached to small particles may get into the air and travel a long way before coming down to earth as dust or in rain or snow. Cadmium does not break down in the environment but can change into different forms. Most cadmium stays where it enters the environment for a long time. Some of the cadmium that enters water will bind to soil but some will remain in the water. Cadmium in soil can enter water or be taken up by plants. Fish, plants, and animals take up cadmium from the environment.

Most cadmium used in this country is extracted during the production of other metals such as zinc, lead, or copper. Cadmium has many uses in industry and consumer products, mainly batteries, pigments, metal coatings, and plastics.

Sources:

Target Organs: Appetite and pain centers (in brain), brain, heart and blood vessels, kidneys, and lungs.

Health effects:  

Current studies are attempting to determine if cadmium-induced bone and kidney damage can be prevented (or made less likely) by adequate calcium, protein (amino acids), vitamin D, and zinc in the diet.

Cadmium is another toxic metal with a long history of detrimental effects. Hair analysis is useful for evaluating cadmium in smoker and nonsmoker populations of industrially non-exposed urban and rural areas. Smoking itself causes significant elevation of toxic element levels in hair, particularly cadmium, lead, and nickel. The urine level of cadmium is also a good measure of body stores. Under most circumstances, measurement of urine levels is a clinically useful technique. Once the renal threshold has been exceeded, however, urine levels become less trustworthy.

Cadmium exposure has been associated with hypertension, and studies show that hair levels of hypertensives are higher than controls. Hair cadmium has also been shown to be significantly and inversely related to the activity of erythrocyte Na+/K+ ATPase among a group of male smokers. This enzymatic inhibition by cadmium was noted at levels far below toxic levels and may provide additional insight into the link between hypertension and cadmium exposure. Cadmium appears to inhibit sulfhydryl-containing enzymes so that relatively low doses depress levels of norepinephrine, serotonin, and acetylcholine.

Cadmium has no known good effects on your health. Breathing air with very high levels of cadmium severely damages the lungs and can cause death. Breathing lower levels for years leads to a build-up of cadmium in the kidneys that can cause kidney disease. Other effects that may occur after breathing cadmium for a long time are lung damage and fragile bones. Workers who inhale cadmium for a long time may have an increased chance of getting lung cancer. No proof has been found that mice or hamsters that breathe in cadmium get lung cancer. However, some rats that breathe in cadmium do develop lung cancer. We do not know if breathing cadmium can affect your ability to have children or can harm unborn babies. Female rats and mice that breathe high levels of cadmium have fewer litters and the pups may have more birth defects than usual. Breathing cadmium causes liver damage and changes in the immune system in rats and mice. We do not know if breathing cadmium harms the liver, heart, nervous system, or immune system in humans.

Eating food or drinking water with very high cadmium levels severely irritates the stomach, leading to vomiting and diarrhea. The only people who have died from drinking cadmium are people who used cadmium to commit suicide. Eating lower levels of cadmium over a long period of time leads to a build-up of cadmium in the kidneys. This cadmium build-up causes kidney damage, and also causes bones to become fragile and break easily. We know that if female rats or mice eat or drink cadmium, their litters may be harmed. We do not know if eating cadmium affects your ability to have children or harms unborn babies. Animals eating or drinking cadmium sometimes get high blood pressure, iron poor blood, liver disease, and nerve or brain damage. We do not know if humans eating or drinking cadmium get any of these diseases. Studies of humans or animals that eat or drink cadmium have not found increases in cancer. These studies were not strong enough to show that eating or drinking cadmium definitely does not cause cancer. The Department of Health and Human Services has determined that cadmium and cadmium compounds may reasonably be anticipated to be carcinogens. The International Agency for Research on Cancer has determined that cadmium is probably carcinogenic to humans. The EPA has determined that cadmium is a probable human carcinogen by inhalation. Skin contact with cadmium is not known to cause health effects in humans or animals.

 

 

 

 

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